Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Bentley, WA 6102, Australia.
Agriculture and Agri-Food Canada, Lethbridge Research and Development Center, Lethbridge, Alberta, Canada.
Phytopathology. 2024 Jul;114(7):1525-1532. doi: 10.1094/PHYTO-10-23-0370-R. Epub 2024 Jun 29.
The necrotrophic effector ToxA is a well-studied virulence factor produced by several fungal necrotrophs. Initially cloned from the wheat tan spot pathogen in 1996, was found almost a decade later in another fungal pathogen, and its sister species, . In 2018, ToxA was detected in a third wheat fungal pathogenic species, , which causes spot blotch disease. However, unlike the case with and , the ToxA in has only been investigated in recent years. In this report, five Australian isolates were assessed for the presence of ToxA. Four isolates were found to contain ToxA. While one isolate harbored the previously reported haplotype sequence (, three isolates contain a different haplotype, designated herein as , which has a nonsynonymous mutation resulting in an amino acid change of glycine to arginine at position 168. Both ToxA isoforms, when heterologously expressed in exhibited the classic ToxA necrosis-inducing activity on ToxA-sensitive cultivars. Preliminary analysis of the isolates in Australian wheat cultivars showed that isolates with , or displayed various degrees of virulence, with the most aggressive isolates observed for those producing ToxA. Differences in spot blotch disease severity between and cultivars were observed; however, this was not limited to the ToxA-producing isolates. The overall results suggest that the virulence of the Australian isolates is diverse, with the significance of ToxA- interactions depending on individual isolates.
坏死性效应因子 ToxA 是几种真菌坏死病原菌产生的一种研究得很好的毒力因子。该因子最初于 1996 年从小麦褐斑病原菌中克隆，近十年后在另一种真菌病原菌—— 和其姊妹种 中被发现。2018 年，ToxA 被检测到存在于第三种小麦真菌病原菌 中，其导致斑点叶枯病。然而，与 和 的情况不同， 中的 ToxA 只是在最近几年才被研究。在本报告中，评估了来自澳大利亚的 5 个 分离株中 ToxA 的存在情况。发现其中 4 个分离株含有 ToxA。虽然一个分离株含有先前报道的 单倍型序列（ ），但另外 3 个分离株含有不同的单倍型，命名为 ，其中存在一个非同义突变，导致第 168 位的甘氨酸突变为精氨酸。当在 中异源表达时，两种 ToxA 同工型都表现出经典的 ToxA 诱导坏死活性，对 ToxA 敏感的 品种具有毒性。对澳大利亚小麦品种中的 分离株进行初步分析表明，携带 、 或 的分离株表现出不同程度的毒性，观察到产生 ToxA 的分离株最为侵袭性。在 和 品种之间观察到斑点叶枯病严重程度的差异；然而，这并不局限于产生 ToxA 的分离株。总体结果表明，澳大利亚 分离株的毒力具有多样性，ToxA-相互作用的意义取决于单个分离株。
